import { useSettings, type ReadReceiptPolicy } from "@/store/settings";
import { Switch } from "@/ui/misc";
import { browserTimeZone, listTimeZones } from "@/lib/dates";
import { toast } from "@/ui/toast";
import { useState } from "react";
import { t } from "@/lib/i18n";
import {
  canUnregisterMailtoHandler,
  isInstalledApp,
  mailtoHandlerRequested,
  mailtoHandlerSupport,
  registerMailtoHandler,
  unregisterMailtoHandler,
} from "@/lib/mailhandler";
import {
  browserLocale,
  formatClock,
  formatDate,
  formatFullDateTime,
  getServerLocale,
  localeLabel,
  localeOptions,
  withPrefs,
  type DateFormat,
} from "@/lib/datetime";

/** Illustrative instant used for the format previews: 22 Nov 2025, 18:23. */
const SAMPLE = new Date(2025, 10, 22, 18, 23);

const DATE_FORMATS: Array<{ value: DateFormat; label: string }> = [
  { value: "auto", label: "Automatic" },
  { value: "dmy-dot", label: "Day.Month.Year" },
  { value: "dmy-slash", label: "Day/Month/Year" },
  { value: "mdy-slash", label: "Month/Day/Year" },
  { value: "ymd-dash", label: "Year-Month-Day (ISO 8601)" },
];

export function GeneralSettings() {
  const s = useSettings((st) => st.settings);
  const update = useSettings((st) => st.update);
  const reset = useSettings((st) => st.reset);
  const exportJson = useSettings((st) => st.exportJson);
  const importJson = useSettings((st) => st.importJson);
  const serverLocale = getServerLocale();
  const autoLocale = serverLocale ?? browserLocale();

  return (
    <div>
      <h1>{t("General")}</h1>
      <p className="lead">{t("Reading, sending and list behaviour. Settings are stored in this browser.")}</p>

      <h2>{t("Reading")}</h2>
      <div className="field-row">
        <div className="field">
          <label>{t("Reading pane")}</label>
          <select className="select" value={s.readingPane} onChange={(e) => update({ readingPane: e.target.value as typeof s.readingPane })}>
            <option value="right">{t("Right of the list")}</option>
            <option value="bottom">{t("Below the list")}</option>
            <option value="off">{t("Off (open messages full width)")}</option>
          </select>
        </div>
        <div className="field">
          <label>{t("Mark as read")}</label>
          <select className="select" value={String(s.markReadDelay)} onChange={(e) => update({ markReadDelay: Number(e.target.value) })}>
            <option value="0">{t("Immediately when opened")}</option>
            <option value="2">{t("After 2 seconds")}</option>
            <option value="5">{t("After 5 seconds")}</option>
            <option value="-1">{t("Never automatically")}</option>
          </select>
        </div>
        <div className="field">
          <label>{t("After archiving or deleting")}</label>
          <select className="select" value={s.autoAdvance} onChange={(e) => update({ autoAdvance: e.target.value as typeof s.autoAdvance })}>
            <option value="list">{t("Go back to the list")}</option>
            <option value="older">{t("Open the next (older) conversation")}</option>
            <option value="newer">{t("Open the previous (newer) conversation")}</option>
          </select>
        </div>
        <div className="field">
          <label>{t("Remote images")}</label>
          <select className="select" value={s.imagePolicy} onChange={(e) => update({ imagePolicy: e.target.value as typeof s.imagePolicy })}>
            <option value="ask">{t("Ask before showing (recommended)")}</option>
            <option value="contacts">{t("Show automatically from my contacts")}</option>
            <option value="always">{t("Always show")}</option>
          </select>
        </div>
      </div>
      <Switch checked={s.conversationMode} onChange={(v) => update({ conversationMode: v })} label={t("Conversation view")} hint={t("Group messages from the same thread together.")} />
      <Switch checked={s.showPreview} onChange={(v) => update({ showPreview: v })} label={t("Show message snippets")} hint={t("Preview the first line of each message in the list.")} />
      <Switch checked={s.showAvatars} onChange={(v) => update({ showAvatars: v })} label={t("Show sender avatars")} />
      <Switch checked={s.confirmDelete} onChange={(v) => update({ confirmDelete: v })} label={t("Confirm before deleting")} />

      <h2>{t("Composing")}</h2>
      <div className="field-row">
        <div className="field">
          <label>{t("Default format")}</label>
          <select className="select" value={s.composeFormat} onChange={(e) => update({ composeFormat: e.target.value as typeof s.composeFormat })}>
            <option value="html">{t("Rich text (HTML)")}</option>
            <option value="text">{t("Plain text")}</option>
          </select>
        </div>
        <div className="field">
          <label>{t("Undo send window")}</label>
          <select className="select" value={String(s.undoSendSeconds)} onChange={(e) => update({ undoSendSeconds: Number(e.target.value) })}>
            <option value="0">{t("Off")}</option>
            <option value="5">{t("5 seconds")}</option>
            <option value="8">{t("8 seconds")}</option>
            <option value="15">{t("15 seconds")}</option>
            <option value="30">{t("30 seconds")}</option>
          </select>
        </div>
      </div>
      <Switch checked={s.includeQuote} onChange={(v) => update({ includeQuote: v })} label={t("Quote original message in replies")} />
      <Switch checked={s.signatureAboveQuote} onChange={(v) => update({ signatureAboveQuote: v })} label={t("Place signature above quoted text")} />
      <Switch checked={s.attachmentReminder} onChange={(v) => update({ attachmentReminder: v })} label={t("Attachment reminder")} hint={t("Warn when the message mentions an attachment but none is attached.")} />
      <Switch checked={s.requestReadReceipt} onChange={(v) => update({ requestReadReceipt: v })} label={t("Always request read receipts")} />
      <div className="field">
        <label>{t("When someone requests a read receipt")}</label>
        <select className="select" value={s.readReceiptPolicy} onChange={(e) => update({ readReceiptPolicy: e.target.value as ReadReceiptPolicy })}>
          <option value="ask">{t("Ask me on each message")}</option>
          <option value="never">{t("Never send one")}</option>
        </select>
        <p className="hint">
          
          {t("A receipt tells whoever asked that this address is live and when the message was read, and the sender chooses where it goes — so there is no automatic option. Bulk mail, mailing lists and anything marked auto-submitted are never offered one at all.")}
        </p>
      </div>
      <Switch checked={s.spellcheck} onChange={(v) => update({ spellcheck: v })} label={t("Spell check while typing")} />

      <h2>{t("Locale")}</h2>
      <div className="field-row">
        <div className="field">
          <label>{t("Time zone")}</label>
          <select className="select" value={s.timeZone ?? ""} onChange={(e) => update({ timeZone: e.target.value || null })}>
            <option value="">Browser default ({browserTimeZone})</option>
            {listTimeZones().map((tz) => <option key={tz} value={tz}>{tz}</option>)}
          </select>
        </div>
        <div className="field">
          <label>{t("Week starts on")}</label>
          <select className="select" value={String(s.weekStart)} onChange={(e) => update({ weekStart: Number(e.target.value) as 0 | 1 | 6 })}>
            <option value="1">{t("Monday")}</option>
            <option value="0">{t("Sunday")}</option>
            <option value="6">{t("Saturday")}</option>
          </select>
        </div>
      </div>
      <div className="field-row">
        <div className="field">
          <label>{t("Language & region")}</label>
          <select className="select" value={s.locale} onChange={(e) => update({ locale: e.target.value })}>
            <option value="">Automatic ({localeLabel(autoLocale)})</option>
            {localeOptions().map((o) => <option key={o.tag} value={o.tag}>{o.label} — {o.tag}</option>)}
          </select>
          <p className="hint">{serverLocale ? `Your mail server reports ${localeLabel(serverLocale)} (${serverLocale}).` : "Your mail server does not report a locale, so the browser's is used."} Dates, times and month names follow this choice.</p>
        </div>
        <div className="field">
          <label>{t("Date format")}</label>
          <select className="select" value={s.dateFormat} onChange={(e) => update({ dateFormat: e.target.value as DateFormat })}>
            {DATE_FORMATS.map((f) => (
              <option key={f.value} value={f.value}>
                {f.label} ({withPrefs({ locale: s.locale, dateFormat: f.value }, () => formatDate(SAMPLE))})
              </option>
            ))}
          </select>
        </div>
        <div className="field">
          <label>{t("Time format")}</label>
          <select className="select" value={s.timeFormat} onChange={(e) => update({ timeFormat: e.target.value as typeof s.timeFormat })}>
            <option value="auto">Automatic ({withPrefs({ locale: s.locale, timeFormat: "auto" }, () => formatClock(SAMPLE))})</option>
            <option value="24">{t("24-hour clock (18:23)")}</option>
            <option value="12">{t("12-hour clock (6:23 PM)")}</option>
          </select>
        </div>
      </div>
      <p className="hint">Preview: {formatFullDateTime(SAMPLE)}</p>

      <h2>{t("Default mail app")}</h2>
      <MailHandlerSettings />

      <h2>{t("Backup")}</h2>
      <div className="row wrap">
        <button className="btn" onClick={() => { const blob = new Blob([exportJson()], { type: "application/json" }); const a = document.createElement("a"); a.href = URL.createObjectURL(blob); a.download = "ihasmail-settings.json"; a.click(); }}>{t("Export settings")}</button>
        <label className="btn">
          Import settings
          <input type="file" accept="application/json" hidden onChange={async (e) => { const f = e.target.files?.[0]; if (!f) return; const ok = importJson(await f.text()); toast[ok ? "success" : "error"](ok ? "Settings imported" : "Invalid settings file"); e.target.value = ""; }} />
        </label>
        <button className="btn btn-ghost" onClick={() => { reset(); toast.show("Settings reset to defaults"); }}>{t("Reset to defaults")}</button>
      </div>
    </div>
  );
}

/**
 * Offer ihasmail as the browser's handler for `mailto:` links. The browser
 * owns the decision, and nothing can read the answer back, so this states what
 * it can and points at the browser's own settings for the rest.
 */
function MailHandlerSettings() {
  const support = mailtoHandlerSupport();
  const [requested, setRequested] = useState(mailtoHandlerRequested);

  const ask = () => {
    try {
      registerMailtoHandler();
      setRequested(true);
      toast.success("Your browser will ask whether to open mail links in ihasmail");
    } catch (err) {
      toast.error(`Your browser refused the request: ${(err as Error).message}`);
    }
  };

  const remove = () => {
    unregisterMailtoHandler();
    setRequested(false);
    toast.show("Removed. Mail links will open in whatever your browser falls back to.");
  };

  if (support === "unsupported") {
    return <p className="hint">This browser cannot register apps for <code>mailto:</code> links. Safari, in particular, has no such API — you can still make ihasmail the default from your operating system if you install it as an app.</p>;
  }
  if (support === "insecure") {
    return <p className="hint">Registering for <code>mailto:</code> links requires a secure (HTTPS) connection.</p>;
  }

  return (
    <>
      <p className="hint">
        Open <code>mailto:</code> links — in web pages, documents and other apps — in ihasmail instead of a desktop mail client.
        Your browser will ask you to confirm, and you can change it later in its own settings (Chrome: Settings › Privacy and security › Site settings › Protocol handlers; Firefox: Settings › General › Applications).
      </p>
      <div className="row wrap">
        <button className="btn btn-primary" onClick={ask}>{requested ? "Ask again" : "Make ihasmail the default mail app"}</button>
        {requested && canUnregisterMailtoHandler() && <button className="btn btn-ghost" onClick={remove}>{t("Remove")}</button>}
      </div>
      {requested && <p className="hint mt-8">{t("Requested in this browser. Whether it took effect is up to the browser — check its settings if mail links still open elsewhere.")}</p>}
      {!isInstalledApp() && (
        <p className="hint mt-8">
          
          {t("For a system-wide default, install ihasmail as an app first (in Chrome: the install icon in the address bar). Your operating system can then offer ihasmail directly wherever it asks which mail app to use.")}
        </p>
      )}
    </>
  );
}